1. Field of Invention
The present invention generally relates to an ink jet print head, and more particularly, to an identification circuit for the ink jet print head and a method thereof.
2. Description of Related Art
Different types of computer peripheral products have been developed and are now widely accepted. For ink jet printers, in order to fulfill different printing requirements for users working in different environments, different types of ink jet printers have been developed. However, each ink jet printer has different types of the ink jet print heads that correspond to it, for example, an ink jet print head with a black cartridge or color cartridge, and ink jet print heads with different number of injection nozzles.
In order to identify the types of the ink jet print head, an identification code corresponding to its model or serial number is given to each ink jet print head when it is manufactured, so that the ink jet printer can identify different types of ink jet print heads when they are installed onto the ink jet printer, so as to use different control programs to control the ink jet print heads of different models or serial numbers.
As described above, since there are many types of the ink jet print heads, an identification circuit that reads one or identification codes corresponding to its model or serial number had better be designed into the ink jet print head to provide the ink jet printer to identify different types of the ink jet print heads installed thereon. Since the identification circuit of the ink jet print head is only used at the moment of the ink jet print head being installed in the ink jet printer or before the first printing operation is started, and once the ink jet print head is identified, the identification circuit can be no longer used. Therefore, it is common that the identification circuit of the ink jet print head reads the identification code stored in the ink jet print head by using the address lines of the print head array.
FIG. 1 schematically shows a block diagram of an ink jet printer identification system. As shown in the drawing, the ink jet printer identification system 100 comprises printer electronics 110 and print head electronics 120, wherein the printer electronics 110 and the print head electronics 120 are connected with each other via a plurality of address lines 131 and a temperature sensing output line 132. The printer electronics 110 comprise a controller 111 and a driving circuit 112, and the print head electronics 120 comprise a print head array 121, an identification circuit 122, and a temperature sensing circuit 123.
When it is printing, the controller 111 transmits the data being printed to the driving circuit 112, and the driving circuit 112 drives the address lines 131, so as to control the print head array 121 to print out the required patterns. The temperature sensing circuit 123 senses the temperature of the print head, and transmits it to the controller 111 via the temperature sensing output line 132. The identification circuit 122 connected to part of the address lines 131 and is used to have the controller 111 send out a control signal for reading out the stored identification code, and to output the stored identification code via the temperature sensing output line 132.
There are several types of the identification circuits in the prior art, the one shown in FIG. 2 is one identification circuit disclosed by U.S. Pat. No. 5,363,134. As shown in the drawing, the identification circuit 200 comprises a plurality of programmable fuses F1˜F13 and a plurality of transistors Q1˜Q13. One end of each of the fuses F1˜F13 is coupled to a corresponding gate of the transistors Q1˜Q13, so as to control the “ON” or “OFF” of the transistors Q1˜Q13. The identification code corresponding to the type of the ink jet print head using this identification circuit 200 is stored via the programmable fuses F1˜F13. Whether each of the fuses F1˜F13 is fused or not represents a bit data of the identification code, respectively.
When the printer intends to read the identification code, a high level reading control signal is sent out via the address lines 131. Here, it is assumed that the high level reading control signal is sent out from A13. If the fuse F13 is reserved, the transistor Q13 is ON, therefore, the temperature sensing output line 132 is dropped down to a low level for reading an identification code of “0”. On the contrary, if the fuse F13 is fused when it is programmed, the transistor Q13 is OFF, and the temperature sensing output line 132 is pulled up to a high level by the pull-up resistor (not shown) of the printer electronics 10 in FIG. 1. Therefore, an identification code of “1” is read out, and the method mentioned above can be used to sequentially read out other bits of the identification code.
Each address line of such type of the identification circuit 200 can only read out one corresponding bit of the identification code. Therefore, the quantity of the bits in the identification code that can be stored in the print head is limited by the number of the address lines, so it is hard to expand.
FIG. 3 shows the other identification circuit disclosed by U.S. Pat. No. 5,940,095. The identification circuit 300 mainly comprises a plurality of one-bit shift registers 320a, 320b, 320c, and 320d for achieving the object of implementing a parallel in, serial out identification circuit. That is, when the printer electronics 110 in FIG. 1 transmits a loading control signal “Load” via the address line 325, the stored identification code is loaded in parallel to the plurality of one-bit shift registers 320a, 320b, 320c, and 320d. Then, when a first clock signal clk1 and a second clock signal clk2 are sequentially received via the address line 326 and 327, respectively, the bit data stored in the one-bit shift register 320d is shifted out via the output line 328. Then, the bit data stored in the one-bit shift register 320c is shifted into the one-bit shift register 320d, the bit data stored in the one-bit shift register 320b is shifted into the one-bit shift register 320c, and the bit data stored in the one-bit shift register 320a is shifted into the one-bit shift register 320b. 
Therefore, after the printer electronics 110 transmits the loading control signal “Load”, and sequentially transmits the required first clock signal clk1 and the required second clock signal clk2 via the address line 326 and 327, respectively, the identification code stored in the plurality of one-bit shift registers 320a, 320b, 320c, and 320d is output sequentially. Therefore, such parallel in, serial out identification circuit 300 is able to expand the bit number of the identification code based on the requirements with only small number of the address lines, such as 325, 326, and 327, so that it is not limited by the number of the address lines.
However, the identification circuit that is able to expand the bit number of the identification code and not be limited by the number of the address lines, is not limited in implementation to the parallel in, serial out identification circuit by using the shift register mentioned above.